This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. This research project is part of an Alzheimer's Disease Research Center (ADRC) grant. The objective of this work is to of this work is to determine whether sensitive behavioral tasks, together with eye-tracking technology, will reveal a profile of performance in MCI patients that is useful in predicting the onset of Alzheimer's disease. The overall plan is to test 60 MCI patients, 60 matched normal control (NC) subjects, 30 patients with Alzheimer's Disease (AD) and a group of 30 Parkinson's Disease patients without dementia (PD). All subjects are recruited from the ADRC Clinical Core. Each subject is tested yearly on two declarative memory tasks and one nondeclarative memory task, together with eye-tracking. We have successfully administered the preferential looking task together with eye-tracking in these subjects and are currently collecting Year 3/Year 4 data. An important contribution from this work would be the ability to diagnose sooner than is now possible in MCI patients oncoming cognitive decline, at a time when the nervous system is less compromised and, accordingly, more likely to benefit from therapeutic intervention.